More than six months into the worst Ebola outbreak in history, there is no clear sense of who is leading the international response, how funds are being collected and disbursed, which organizations are providing equipment and personnel, and when any of these efforts will make a significant difference in slowing the epidemic in West Africa.

The confusion and lack of coordination have delayed shipments of desperately needed supplies; some of those being pledged now won’t arrive for months. For example, a 62-bed facility that the British government on Monday promised to deliver will take eight weeks to be operational; the 25-bed field hospital the Pentagon has offered will take at least a month before it is up and running.

The lagging response means that the relief effort is three to four months behind where it should be, given the seriousness of the epidemic, health experts say.

“There is no one who is really in charge with the capacity and the ability to completely lead the international response,” said Josh Michaud, associate director of U.S. global health policy at the Kaiser Family Foundation.

With the exception of the international aid group Doctors Without Borders, global health officials were caught off guard by the severity of the outbreak. The World Health Organization underestimated its complexity and magnitude, and now a rapidly rising caseload is far outstripping the ability of aid groups, regional ­governments and international health officials to bring it under control.

“Where we are today is probably where we should have been in May,” said Ken Isaacs, a former director of foreign disaster assistance at the U.S. Agency for International Development, and a vice president at Samaritan’s Purse, a Christian aid organization that has been active in the region.

The responses were far different for other international disasters in recent years. When a tsunami hit Indonesia in 2004, and an earthquake struck Haiti in 2010, governments and international health authorities rushed to offer money, manpower and other forms of aid.

Those disasters killed hundreds of thousands of people — many more than the nearly 2,300 for the current Ebola outbreak. And even though the actual Ebola fatalities are probably much higher, the epidemic has not been “a big, acute event that everyone can rally around,” Michaud said. “This has been on a slow burn for a while” in five nations in West Africa.

The slow burn, however, is now “spreading like wildfire, devouring everything in its path,” Liberia’s defense minister, Brownie Samukai, told the U.N. Security Council this week. He said that Liberia, which was torn by two civil wars that left more than 250,000 dead, is “facing a serious threat to its national existence.”

The Ebola epidemic, experts say, has highlighted dangerous gaps in the world’s ability to respond to deadly pathogens. The three countries hit hardest by the epidemic are among the poorest in the world, with health systems and other infrastructure so decimated by civil war and conflict that they are barely able to provide basic care. At the same time, the WHO has been so ravaged by budget cuts and the loss of staff in recent years that it is “a shadow of its former self, racing to regain its own credibility in this crisis,” said Laurie Garrett, senior fellow for global health at the Council on Foreign Relations and author of one book about the 1976 Ebola epidemic and another about the global health system.

Garrett said that she spoke to public health workers in the region Thursday and that they estimate the number of people in West Africa stricken with Ebola, including those who have died, will be 250,000 by November.

Meanwhile, top officials at the United Nations and within the U.S. government and its allies are scrambling to improve their response. In Washington, Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, convened a meeting Wednesday on the situation, according to Garrett, who attended the session and warned the other participants of widespread regional instability if the outbreak is not halted.

The Ebola epidemic over time

Administration officials have said U.S. military involvement will reflect President Obama’s decision to treat the epidemic as a national security concern but have not provided details.

But Garrett noted that the U.S. military is stretched thin and faces more demands in the Middle East and elsewhere.

“The cavalry is not going to ride to the rescue,” she said Thursday, addressing a global health conference. “At least not in the numbers people are dreaming of.”

At the United Nations, meanwhile, David Nabarro, who was put in charge of coordinating the international response last month, said the challenges are numerous.

“We are trying to knit together one of the most complicated coalitions of support that we have ever been involved in,” he said in an interview last week from Geneva, adding that Ebola was “the number one global crisis” for the United Nations.

Nabarro predicted that there would be a “massive” improvement in the situation in Liberia and Sierra Leone within four weeks, adding that officials are focusing on helping national governments manage the crisis rather than bringing in outsiders to take over the relief effort.

But some aid experts say that approach is wrong. More outside direction is needed, especially from the U.S. military because of its enormous logistical capacity, extensive air operations and highly trained medical corps.

“Why would the world allow what is potentially a global epidemic to be managed by three of the poorest countries in the world?” said Isaacs of Samaritan’s Purse.

“There’s not a high level of confidence in the ministries of health in these countries to equitably distribute goods to where they are needed,” he said. “They don’t even have ambulances to move people to the clinics, not to mention all the corruption.”

Nabarro has estimated that it will cost at least $600 million to fight the epidemic and deal with the broader economic and social devastation suffered by the hardest-hit countries — Liberia, Sierra Leone and Guinea.

The U.S. government has spent more than $100 million in the region, and additional requests for aid, if approved by Congress, would bring the total commitment to more than $250 million. The United States is providing logistical and operational support, including personal protective equipment, mobile labs and other basic supplies and food.

The biggest need is for skilled personnel to relieve exhausted health-care workers.

But a top U.S. official said this week that the only workforce with experience in treating Ebola is Doctors Without Borders. The WHO is training 500 workers in the special protocols needed to prevent transmission.

The World Bank is working with the United Nations to set up a system to track donations and distribution of funds, a senior bank official said. The bank has also pledged a $230 million aid package, including $117 million in emergency response, most of it in grants.

World Bank President Jim Yong Kim, an infectious disease expert, also organized a task force last week to develop a standard protocol for all health-care workers to follow at treatment centers in the region.

Countries and organizations have also increased pledges and donations. But so far, there is no central account to receive corporate private donations. And aid groups say there isn’t even a master list of the most urgent items and tasks.

“Everybody would like to get a matrix of what are the needs for burial, for treatment centers, for [disease] surveillance,” said Joanne Liu, international president of Doctors Without Borders. Because the group has been the most active aid group from early in the epidemic and has 2,000 staff members working in the three countries, it was asked by the international community to provide such a list.

But Liu said the group is overwhelmed. “We are burying people and treating patients,” she said. “We are doing everything, and no one is coming out to relieve us from any of those activities.”

Brady Dennis contributed to this report.